Wrapping apparatuses have been developed to stretch, dispense, and wrap stretch packaging material around a load. The four vertical sides of the load are typically covers with a stretchable packaging material (or film) such as polyethylene packaging material. Stretch wrapping can be accomplished by a turntable, a rotating arm, a vertical rotating ring, or a horizontal rotating ring wherein relative rotation is provided between the load and a packaging material dispenser to wrap packaging material about the sides of the load.
Loads are continuously packaged in the wrapping apparatus until the packaging material supply mounted to the packaging material dispenser is emptied. Then, the packaging material dispenser must be reloaded with a new packaging material supply. Alternatively, even if the packaging material dispenser is not emptied, there may be a need to change the packaging material, for instance, to wrap a load with a packaging material having different properties. For reloading the packaging material dispenser with a new packaging material supply or changing the packaging material, an operator must enter the wrap zone and, consequently, energy has to be removed from the apparatus. Furthermore, when the wrapping apparatus is restarted, energy has to be restored beforehand. There is thus a downtime period associated with either reloading the packaging material dispenser or changing the packaging material.
Furthermore, in some applications, there might be a need to at least partially wrap an upper surface of the load. However, when using a turntable to provide relative rotation between the load and the packaging material dispenser, pressure must be applied on the load upper surface to prevent the latter from being ejected from the turntable due to the centrifugal force. There is thus a need to apply pressure on the upper surface of the load to prevent load ejection from the turntable or displacement of the load during rotation and simultaneously allow at least a portion of the upper surface to be covered by the packaging material.